The field of this invention relates to bicycles and more particularly to a power transmitting crank assembly which is commonly employed in conjunction with bicycles in order to transmit motive power from the legs of the user of the bicycle to the rear wheel of the bicycle.
The use of foot operated crank assemblies within bicycles is well known. In recent years, there has been developing a new sport which amounts to racing of dirt bicycles. A dirt bicycle has a wheel diameter of approximately twenty inches. This size of wheel is desirable when racing on dirt tracks, as opposed to racing on streets. The street bicycle will use a substantially larger diameter wheel.
In the racing of bicycles on dirt, the bicycle is frequently subjected to unexpected forces. These unexpected forces have to do with the uneven terrain. Additionally, the operator of the bicycle is constantly subjecting a substantial amount of torque to the foot operated crank assembly of the bicycle. This level of torque may be sufficient, after a few races, to damage the crank assembly requiring replacement.
Also, in the racing of bicycles, if a sprocket wheel, or other portion of the crank assembly of the bicycle, becomes damaged, it would be desirable to facilitate quick replacement of that part thereby permitting the participant to continue in the race. Additionally, in the short period of time between races, it may be desirable, because of different racing conditions, to change from one size sprocket wheel to another size sprocket wheel. Again, quick replacement of the sprocket wheel would be desirable.
Within prior art bicycles, the quick replacement of the sprocket wheel has not been possible. Therefore, if any portion of the crank assembly becomes damaged, the participant is forced to withdraw from the race. Additionally, the changing of any sprocket, or any portion of the crank assembly between races has heretofore not been feasible, as usually insufficient time is permitted.